System and method for underactuated control of insertion path for asymmetric tip needles

ABSTRACT

A needle steering system and apparatus provides active, semi-autonomous control of needle insertion paths while still enabling a clinician ultimate control over needle insertion. The present teaching describes a method and system for controlling needle path as the needle is inserted by precisely controlling the rotation of the needle as it continuously rotates during insertion. This enables underactuated 2 degree-of-freedom (DOF) control of the direction and the curvature of the needle from a single rotary actuator. Control of the rotary motion is therefore decoupled from the needle insertion. The rotary motion controls steering effort and direction, while the insertion controls needle depth or insertion speed. In one implementation, the proposed method does not require constant velocity insertion, interleaved insertion and rotation, or known insertion position or speed. The insertion may be provided by a robot or other automated method, may be a manual insertion, or may be a teleoperated insertion

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of earlier filedU.S. Provisional Application Ser. No. 61/715,063, filed Oct. 17, 2012,entitled “SYSTEM AND METHOD FOR UNDERACTUATED CONTROL OF INSERTION PATHFOR ASYMMETRIC TIP NEEDLES” the teachings, disclosures and contents ofwhich are incorporated herein by reference in entirety.

FIELD OF INVENTION

The disclosed configuration relates to a system and approach forcontrolling insertion paths of needles with asymmetric tips fortherapeutic and diagnostic medical interventions, and especiallyunderactuated control of needle curvature and direction decoupled fromneedle insertion.

BACKGROUND

Needle-based interventions are commonplace. These may be used for avariety of percutaneous diagnostic and therapeutic interventions.However, ensuring that the needle, cannula, or other instrument makes itto the desired target while following a desired path is oftennontrivial. Inaccuracy may come from various causes including needledeflection, tissue deformation, target motion, patient motion, or othersources. Many needles have asymmetric tip shapes, such as a beveled tipand/or cannula. In some cases, these tips cause asymmetric forces on theneedle that cause it to deflect as it is inserted. This deflection inmany cases is undesirable and results in errors in needle placement.However, some clinicians use the asymmetric tip forces to theiradvantage and actively control or steer the needle path during insertionby rotating the bevel direction. Further, others have attemptedcontinuous rotation or drilling of a needle to ensure that it follows astraight insertion path.

SUMMARY

The present disclosure teaches active, semi-autonomous control of needleinsertion paths while still enabling a clinician ultimate control overneedle insertion. The present teaching describes a method and system forcontrolling needle path as the needle is inserted by preciselycontrolling the rotation of the needle as it continuously rotates duringinsertion. This enables underactuated 2 degree-of-freedom (DOF) controlof the direction and the curvature of the needle from a single rotaryactuator. An advantage of the disclosed configuration is that control ofthe rotary motion may be decoupled from the needle insertion. The rotarymotion controls steering effort and direction, while the insertioncontrols needle depth or insertion speed. In one implementation, theproposed method does not require constant velocity insertion,interleaved insertion and rotation, or known insertion position orspeed. The insertion may be provided by a robot or other automatedmethod, may be a manual insertion, or may be a teleoperated insertion.

Control of the needle path may be used in multiple cases. In one case,as the needle is inserted an error is determined between the projectionof the needle and the target, so a compensation in the needle path isrequired. In other cases, a specific path or trajectory is desired, andthe needle is controlled along that path to reach the target. In acombined case, a predetermined path is defined, and compensation isrequired as the needle is inserted to ensure the path is followed andthe endpoint reached. These control approaches may be open loop orclosed loop. The closed loop approach may be based upon medical imagingor image-guidance such as ultrasound, x-ray, fluoroscopy, computedtomography (CT), magnetic resonance imaging (MRI), video feeds, laserscans, external tracking systems, or other approaches.

The present teaching relates generally to controlling the trajectory ofa needle or other instrument with an asymmetric tip. The disclosedarrangement describes a method for underactuated control of needledirection and curvature as it is inserted into tissue that is decoupledfrom the needle insertion motion. The approach also describes a systemand components for implementing the proposed method.

In a particular configuration, the disclosed approach employs a methodfor inserting a needle with a asymmetric shaped tip into tissue along acurved path, wherein the needle is continuously rotated at atime-varying angular velocity; wherein the time-varying angular velocityrotation is a function of the needle angular position.

An example needle steering apparatus suitable for use withconfigurations herein includes a needle having an asymmetric tip, theasymmetric tip defined by a beveled cut across a cylindrical crosssection of the needle, and a rotary drive for rotating the needle alonga needle axis. The rotary drive is responsive to control logic adaptedto rotate the needle at an angular velocity based on an angularposition, and invokes an inserter for disposing the needle axially in adirection of an axis of rotation, such that the angular velocity isindependent from the insertion.

In operation, in a surgical environment having an asymmetric tippedneedle and a needle driving apparatus responsive to rotational andinsertion control, the method of directing the needle includesidentifying a steering trajectory path for the needle, and controlling atime-varying rotation speed of the needle based on the identifiedsteering path, such that the rotation speed determines a relativeduration that a bevel angle of the needle applies force in a directioncorresponding to the steering trajectory. The rotation is decoupled fromadvancement of the needle resulting from control of the controlledrotation speed about the needle axis, such that the controlled rotationspeed is based on an angle of rotation, and independent of the linearadvancement of the needle from the insertion control, so that the needlefollows the prescribed path regardless of the insertion speed.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following description of particularembodiments of the invention, as illustrated in the accompanyingdrawings in which like reference characters refer to the same partsthroughout the different views. The drawings are not necessarily toscale, emphasis instead being placed upon illustrating the principles ofthe invention.

FIG. 1 shows a context diagram of major components of the steerableneedle assembly and mechanism suitable for use with configurationsherein;

FIG. 2 shows one implementation of the control algorithm for determiningneedle angular velocity as a function of a current angle;

FIG. 3 shows a representation of how needle curvature is affected bychanging the steering effort parameter;

FIGS. 4 a and 4 b show plots of needle rotation during a controlledinsertion

FIGS. 5 a-5 c show exemplary plot of needle insertion path during acontrolled insertion where needle is inserted straight and then atconstant curvature;

FIGS. 6 a-c demonstrate an example where the same overall needle path isachieved with two different configurations;

FIG. 7 shows a view of the needle path in 3D for the case of straight,then curved insertion;

FIGS. 8 a-8 c show a controlled insertion path where the steeringdirection changes during the course of insertion;

FIG. 9 depicts complex trajectories by combining segments of constantcurvature;

FIG. 10 depicts one embodiment wherein needle curvature during insertionis controlled by a stand-alone device for implementing the needlesteering control;

FIG. 11 depicts a particular configuration employing a robot having aneedle rotation module;

FIG. 12 depicts a configuration of the robotic needle driver module 221that can be used with the robot device of FIG. 11;

FIG. 13 shows a driver module that can hold standard needles;

FIG. 14 depicts one embodiment of the system where an asymmetric tipneedle is concentric with one or more additional cannulas;

FIG. 15 depicts one exemplary embodiment of a robotic needle drivercapable of manipulating both a precurved cannula;

FIG. 16 shows a representative teleoperation framework;

FIG. 17 depicts an example of a teleoperation master; and

FIG. 18 depicts a needle driver module incorporating a force sensor.

DETAILED DESCRIPTION

Configurations disclosed below teach a mechanism referred to as theContinuous Uncoupled Rotation Velocity-independent (CURV) steeringapproach. The described approach is one example, however the disclosedconfiguration also includes other related variants of decoupled,underactuated control of needle insertion based on asymmetric tips. Thedisclosed configuration also describes a plethora of systems andcomponents for implementing the proposed approach. In one embodiment, arobotic needle driver provides 2 DOF control of needle rotation andinsertion, thus providing 3 DOF control of the tip (i.e. can place thetip to a 3D position using 2 actuators). The needle driver may furtherbe configured as part of a robotic system. The system may further beconfigured to incorporate a teleoperation master that a user manipulatesto control needle insertion and/or steering angle. The configuration mayfurther include force sensing and haptic feedback. The haptic feedbackmay be related to the forces on the needle, errors determined by acontrol system, external factors, or some combination of factors. In oneconfiguration, a user manipulates the teleoperation master along onlythe insertion axis to control the insertion depth, while the robotautomatically steers the needle path according to the disclosedconfiguration. This may be used based on preoperative path planning, oractively and semi-autonomously compensating for errors as the needle isinserted. In a further embodiment, the rotation is manipulated accordingto the disclosed configuration by an actuator in a standalone device,and in particular configurations the device may be handheld. The devicecan control steering effort (related to needle curvature in tissueduring insertion) and in alternate configurations may also control angleand/or depth relative to the handle. In an additional embodiment of thedisclosed approach, the asymmetric tip control methods taught in thedisclosed configuration may be coupled with concentric precurved orprebent tubes or cannulas to provide additional dexterity and controlduring needle insertion.

Additional advantages of the disclosed configuration will become readilyapparent to those skilled in this art from the following detaileddescription, wherein only selected embodiments of the disclosedconfiguration are shown and described. As will be realized, thedisclosed configuration is capable of other and different embodiments,and its several details are capable of modifications in various obviousrespects, all without departing from the invention disclosed herein.Accordingly, the drawings and description are to be regarded asillustrative in nature, and not as restrictive.

The present teachings are described more fully hereinafter withreference to the accompanying drawings, in which the present embodimentsare shown. The following description is presented for illustrativepurposes only and the presented teachings should not be limited to theseembodiments.

In this disclosure, the term “needle” is defined as cylindricalinstrument that interacts with tissues, including but not limited tomedical needles, electrodes, tubes, rods, and cannulae. The term needleaxis refers to the axis along the needle, or subsection thereof. Theneedles can typically be inserted and rotated along and about thus axis,respectively. In some cases torsional affects make the rotation atvarious points along the needle unequal, and this can be compensated forif necessary to control the desired subsection of the needle, such asthe tip form the base. The term asymmetric tip generally refers to abevel-shaped tip on a needle, however more broadly it is defined as anyfeature on a needle that provide asymmetric forces that alter theinsertion path as it is inserted.

The examples and discussion that follows employ a surgical context as anexample implementation, such that the a surgical needle or cannulatedinstrument adapted for surgical use is a steerable member, and a mediumemployed for drilling is surgical tissue. Alternate configurations mayemploy alternate arrangements of a steerable member and a medium. Forexample, geological applications may employ steering for exploration ofgeological structures, such as rock and soil. Alternate configurationsmay also be employed for building materials such as concrete or wood, orother medium responsive to the steering methodology disclosed herein.

FIG. 1 shows a context diagram of major components of the steerableneedle assembly and mechanism suitable for use with configurationsherein. Referring to FIG. 1, in a surgical environment 100, a surgicalneedle 110 rotates about a needle axis 112 responsive to a drive shaft114. Surgical needle 110 may be a solid rod, or may be comprised ofmultiple coaxial elements. A hub 116 or other coupling engages theneedle 110 to the hub 116 for engaging a drive source 120, such as anelectric or pneumatic motor, for rotating the drive shaft 114. Hub 116may comprise a disposable, sterilizable collet or other coupling deviceto couple needle 110 to drive 120. The drive 120 is responsive tocontrol logic 122 for controlling rotation for providing the steeringcapability, as disclosed further below. An inserter 130 or other sourceof movement provides linear translation for inserting 132 or withdrawing134 the needle 110, shown by respective arrows. Control logic 122 may beresponsible for controlling rotation drive 120 and translation inserter130, or it may only control rotation drive 120 independent of inserter130. Control logic 122 may be incorporated into an external device suchas a robot controller that controls one or more DOF of the device.Translation may be provided by any suitable mechanism, such as a linearactuator (hydraulic, pneumatic or electric), threaded engagement, manualinsertion, or other suitable force. The needle 110 has a needleinsertion control angle 140 defined by a bevel cut across a crosssection of the needle 110 or at least one of its components. In otherwords, in a cannulated needle arrangement, either the inner needle orthe outer cannula may be beveled, or both may share a coplanar beveledface 142 for greater steering capability. The bevel cut defines a bevelface 142 at the needle insertion control angle 140 with respect to theneedle axis 112, collectively defining an asymmetric tip 144 at the endof the needle frame 146, forming the integral needle 110 structure.Needle frame 146 refers to a coordinate frame fixed to a point at ornear the tip of the needle. Insertion of the needle 110 by the inserter130 into a surgical material 150 or other medium, typically soft tissue,coupled with rotation by the drive 120, causes the bevel face 142 toengage and displace the surgical material 150 or other medium forsteering the needle along a desired path 152, as shown by dotted lines.Steering ability is responsive to varying the rotation speed, discussedbelow, independently of the insertion speed. FIG. 2 shows oneimplementation of the control algorithm for determining needle angularvelocity as a function current angle. Referring to FIG. 2, this approachenables control of steering effort (related to needle path curvature)and the steering direction using only one actuated rotationdegree-of-freedom. The approach is decoupled from the needle insertionmotion.

In one embodiment of the disclosed configuration, the needle pathdirection and curvature is controlled using the approach detailed belowand shown in FIG. 2. In this approach, the needle is continuouslyrotated, and the rotation angle of the needle about its primary axis iscomputed as a function of the current angle and the desired direction.

In one approach, the normalized angular velocity of the needle about itsprimary axis is defined using the Gaussian distribution as:

${\hat{\omega}\left( {\theta,\theta_{d}} \right)} = {1 - {\alpha \; ^{- \frac{{({\theta - \theta_{d}})}^{2}}{2\; c^{2}}}}}$

Where:

-   -   {circumflex over (ω)}(θ, θ_(d)): normalized needle rotation        angular velocity about its primary axis    -   θ: current needle angle about its primary axis    -   θ_(d): needle rotation angle corresponding to desired steering        direction    -   α: steering effort where 1 is maximum steering curvature and 0        is a straight path    -   c: tuning parameter related to width of the distribution about        ν_(d)        The equation above describes the use of a normal, Gaussian        distribution to determine the angular velocity, {circumflex over        (ω)}, of the needle about its primary axis as a function of the        difference between current needle angle, θ, and desired        direction, θ_(d), and is shown representatively in FIG. 2. It        should be noted that other distributions or functions may be        utilized to replace the Gaussian distribution. A primary        contribution of the disclosed approach is underactuated control        of the needle such that curvature and direction of the needle        insertion path can be controlled based on determining the        angular velocity or differential motion as a function of the        rotation angle as the needle rotates continuously. Needle        rotation velocity is determined as a function of the needle        angle as it rotates continuously. The underactuated approach        allows control of curvature and direction from a single rotary        actuator.

The calculation is performed continuously as the needle rotates todetermine the corresponding angular velocity or angle set point.

In one embodiment, needle steering is implemented in software on acontrol system where the normalized needle rotation angular velocity iscalculated in a control loop running at a fixed timer period such as aservo loop running at 1 kHz. The angular velocity of the needle aboutits primary axis as a function of current angle as it rotates iscalculated as:

{dot over (θ)}(θ)=ω_(max){circumflex over (ω)}

Where:

-   -   {dot over (θ)}(θ): needle rotation angular velocity about its        primary axis    -   {circumflex over (ω)}: normalized needle rotation angular        velocity about its primary axis    -   ω_(max): maximum angular velocity of needle about its primary        axis

In one implementation, a discrete time controller is used to determinean angle set point for the next period based on the desired angularvelocity as:

θ(t+1)=θ(t)+ω_(max) {circumflex over (ω)}T

Where:

-   -   θ(t+1): needle rotation angle set point for next period    -   θ(t): needle rotation angle in current period    -   {circumflex over (ω)}: normalized needle rotation angular        velocity about its primary axis    -   ω_(max): maximum angular velocity of needle about its primary        axis    -   T: time period between cycles of control loop

This disclosure refers to the term steering effort which is directlyrelated to curvature, wherein full steering effort corresponds to themaximum curvature and zero steering effort corresponds to a straightinsertion with no curvature. In closed loop control, steering effort isused within the control loop to correct a needle insertion path based ona detected error. FIG. 3 shows an exemplary representation of how needlecurvature is affected by changing the steering effort parameter, i.e. arepresentation of how the steering effort, α, relates to the curvatureof the needle as it is inserted. Referring to FIG. 3, the overall needlecurvature is adjusted by changing this parameter 160. A horizontal axis162 shows an insertion axis corresponding to the drive (needle) axis 112(prior to any steering). A vertical axis 164 shows the lateraldisplacement due to steering, or y-axis. The plot is shown in the planeof the needle's curvature, which may be rotated to any angle about theneedle axis, thus enabling control of the needle tip position and thepath in 3D. Note that this shows the overall curvature of the needlepath, as the tip 144 location during insertion follows a helical profileas the needle rotates during insertion (shown below in FIGS. 6 a, 6 b, 7and 8 a). The size of the helix may be minimized to provide trajectoriesthat appear as shown. For a fixed steering effort, typically the needlewill follow a constant curvature path when all other parameters areconstant. The relationship between steering effort and curvature dependson properties of the needle 110, tissue 150, external forces and controlparameters.

The specific curvature for a given steering effort is also related toneedle properties, tissue properties, and external forces. The steeringeffort may be run open loop to drive the needle along a specific path,it may be controlled in a closed loop to follow a specific path, or itmay be used as a control input to steer the needle towards the target,much like a steering wheel on a car.

FIGS. 4 a and 4 b show plots of needle rotation during a controlledinsertion. Referring to FIG. 4 a, an example of the needle rotationangle about its axis as it spins continuously is show, plotting needle110 angle as a function of time. The vertical axis 166 shows therotation cycle (0-360 degrees), and the horizontal axis 168 shows timefor each rotation. The region where the angle θ remains closest tohorizontal 169 is centered around θ_(d) with a width related to thetuning parameter c and the steering effort α. FIG. 4 b shows thecorresponding angular velocity (derivative of the plot in FIG. 4 a, alsoreferred to as rotation speed), showing needle 110 angular velocity as afunction of time. Note that the angular velocity changes as the needlerotates continuously, where the speed is slower centered on the desiredsteering direction. The shown pattern repeats with a period related tothe set maximum needle rotation angular velocity. The constant velocitysegments are at the defined value for ω_(max). at 170. Note that FIGS. 4a and 4 b correspond to a representative simulation and that varyingcontrol parameters or the specific relationship between angular velocityand angle will vary the shape of the curves. However, the key featuresare the reduced velocity corresponding to being at or near the desiredsteering direction.

FIGS. 5 a-c show exemplary plots of needle insertion path during acontrolled insertion where needle is inserted straight and then at aconstant curvature. Note that the angular velocity is constant duringstraight insertion (i.e. drilling during insertion), and varies aspreviously described during the constant curvature segment. In FIG. 5 a,the X-axis 172 (horizontal) represents the displacement along theinitial insertion direction and y 174 corresponds to the displacement insteering direction for this example. FIG. 5 b is a corresponding plotshowing needle angle 176 with respect to time 178. FIG. 5 c is acorresponding plot showing needle angular velocity 180 with respect totime 182. Note that the angular velocity 180 is constant during straightinsertion (i.e. drilling during insertion), and varies as previouslydescribed during the constant curvature segment. Multiple constantcurvature segments may be cascaded together, shown further below in FIG.14.

FIGS. 6 a-c demonstrate an example where the same overall needle path isachieved with two different configurations, demonstrating needleinsertion where the needle goes straight (with constant angular velocityneedle rotation) for 50 seconds and then constant curvature (usingproposed approach) for 50 seconds. FIG. 6 a shows a small diameter helixof tip 144 position during insertion is formed when rotation speed ishigh relative to insertion speed. FIG. 6 b shows a larger diameter helixformed when rotation speed is low relative to insertion. FIG. 6 cdepicts that the overall needle path (i.e. the path following the centerof the helix) is the same for both cases.

In FIGS. 6 a and 6 b, plot lines 186-1, 186-2 show the shape of the bodyof the needle after insertion and the corresponding needle angularposition and velocity. Plot lines 184-1, 184-2 show the 3D viewincluding the helix that the tip 144 follows as the needle is inserted.The shown helix is exaggerated and can be made negligible withappropriate configuration. Even in the case of straight insertion withconstant angular velocity rotation (i.e. drilling), an asymmetric tipneedle may follow a helical pitch during insertion.

The insertion is decoupled from the insertion speed, this the overallneedle shape at the end of insertion is essentially the same independentof insertion speed. The size of the helical path around that needleshape varies as a function of the relative insertion and rotation speed.For a high rotation speed or low insertion speed, the needle tip pathessentially matches the final needle shape after insertion (i.e.negligible helical tip motion).

FIG. 7 shows a view of the needle path in 3D for the case of straight,then curved insertion. The example 3D view shows tip 188 and frame 190plots of a controlled needle insertion where the needle goes straight,and then continues with constant curvature. Note that the needle tip 144moves in a helical pattern (exaggerated in this figure), where the sizeof the helix is a function of the needle and interaction parameters aswell as the relative insertion speed to rotation speed. The frame 146represents a point set back from the tip on the needle and representsthe needle path. This is a representative case of where a needle isdriven straight towards an intended target, and then needs to becompensated in order to account for target motion or other errorsintroduced during the procedure. The figure shows both the exaggeratedtip position as it is inserted and the frame position which is set backfrom the tip which better represents the final needle shape afterinsertion.

FIGS. 8 a-8 c shows a representative controlled insertion path where thesteering direction changes during the course of insertion. Referring toFIG. 8, the needle 110 inserts straight, then at constant curvature inone direction, and then changes to a different constant curvature in adifferent direction. Therefore, FIG. 8 a depicts an example where theneedle 110, tip 192 and frame 194 paths are controlled according to thepresent configuration along one constant curvature path after a shortstraight insertion, and then the steering direction and steering effortchange to another constant curvature path in a different plane, inresponse to varied rotation angle 196 and rotation speed 198. Many suchpaths may be combined together to generate complex 3D trajectories or tocontinuously compensate for 3D positioning error during insertion. Notehow the angular position and velocity plots show distinct differences inthe three sections of the needle insertion trajectory.

FIG. 9 depicts how the proposed approach allows for complex trajectoriesby combining segments of constant curvature. Referring to FIG. 9, Theproposed approach allows for complex trajectories by combining segments200-1 . . . 200-3 (200 generally) of constant curvature. FIG. 9demonstrates one example of three segments 200, each with a givencurvature (set by steering effort) and a given steering direction (notnecessarily in the same plane as shown). Accordingly, FIG. 9demonstrates one example of three segments, each with a given curvature(set by steering effort) and a given steering direction (not necessarilyin the same plane as shown). Large numbers of constant curvaturesegments may be combined to provide arbitrary paths. The paths of thesegments 200 may be precomputed and run open loop, or may be computed onthe fly based on closed loop feedback. The shape of the needle 110during insertion may be determined from any suitable approach including,but not limited to, medical imaging including projection and tomographicimages, and strain sensors along the needle including fiber bragggrating (FBG) or fabry-perot interferometry (FPI) sensor. Models may beused to estimate shape based on sparse information such as a smallnumber of cross-sectional images rather than requiring a full 3Drepresentation.

FIG. 10 depicts one embodiment wherein needle curvature during insertionis controlled by a stand-alone device for implementing the needlesteering control approach described in the disclosed configuration. Inthe approach of FIG. 10, needle curvature during insertion is controlledby a stand-alone device that controls steering effort by controllingrotation speed as a function of rotation angle as described in thedisclosed configuration. In one embodiment, the device is a handhelddevice with an integrated actuation unit and steering effort may becontrolled by the user. The stand-alone device 210 controls steeringeffort, thus curvature, by controlling rotation speed as a function ofrotation angle as described above. In one embodiment, the device 210 isa handheld device with an integrated actuation unit 212. Steering effortmay be fixed or controlled using a switch 214 or other user input. Theactuation unit 212 provides rotation of the needle 110. In a furtherembodiment it also includes needle insertion that can be used forcontrolling the depth, stabilizing the insertion speed, inserting athigh speed, or modulating the insertion. The device 210 may have anintegrated needle, or it may have a needle fixation component such as ahub 116 or collet to attach the needle 110. In one embodiment thedirection is fixed relative to a handle 216 and marked with an alignmentkey 217, such that direction is controlled by the user and the deviceautomatically controls curvature. In a further embodiment there is anadditional input from user or external source to control the directionrelative to the handle. The device 210 may be tracked externally andincorporate semi-autonomous shared control. It should be noted that thedevice 210 is responsive to manual insertion force provided by anoperator, i.e. direct hand pressure.

In one configuration, the handheld device contains a motor, angularposition sensor, steering effort control switch, processor, and battery.The device may be fully self contained and steers the needle with acurvature related to the steering effort input. The user may use thiswith independently obtained interactively updated or real-time imaging.The device may also incorporate a biopsy sample retrieval mechanism. Anembodiment of the device may be single use or limited lifetime. Thisconfiguration may be used for percutaneous procedures or other access tointernal tissues. It may also be used for accessing structures close tothe surface such as cannulation of blood vessels, acupuncture, or othermedical procedures. In one embodiment, the device is fully compatiblewith the MRI environment and may be used during MR imaging withoutsignificantly degrading image quality.

FIG. 11 depicts a particular configuration of a robotic device 220 toimplement the proposed approach for percutaneous interventions. Therobot 220 has a needle rotation module 222 packaged in a robotic needledriver module 221 that controls needle angle and holds the asymmetrictip needle 110, which may be a cannulated 113 needle. Needle rotationmodule 222 is coupled to control logic 122 that may be integrated intomodule 221 or incorporated into an external device. The needle rotationmodule 222 resides on a needle insertion module 224, such as an inserter130, that may have decoupled control from the needle rotation duringcontrolled needle insertion. In one embodiment, a Cartesian stage 226positions the needle entry point for horizontal translation and verticalorientation via gantry style supports 225, and a fiducial frame 228 isused to localize the robot with respect to the patient or plan. In oneembodiment, the fiducial frame 228 employs a z-shaped fiducial patternto enable localization of the robot and registration to a medicalimaging system (e.g. registered to an MRI scanner's patient coordinateframe). Additional methods of actuated or manual positioning may also beutilized.

FIG. 12 depicts one embodiment of the robotic needle driver module 221that can be used with the robot device 220 in depicted in FIG. 11,another robot, or independently. As above, a module or drive 120controls needle rotation, in this example a piezoelectric motor is used.A further actuator may be used to control a stylet inside of the cannulaof a concentric needle. This example shows a standard needle coupled tothe robot using a collet.

In this embodiment, a collect 116 holds the asymmetric needle 110 andenables control of rotation about the needle axis 112 and insertiontranslation. The drive 120 includes a rotary motor 232 for providing thedrive 120. A piezoelectric motor 233 or other suitable drive provides aseparate rotation source for a cannula 113, augmented by one or morepulleys 230 and belts 234 for controlling rotation of the cannula 113and/or needle 110 inserted therethrough, as is known with surgicalcannulas. The drive 120 may be further facilitated by an eccentric belttensioner 236, bearings 238, and a linear optical encoder 240 formeasuring translation 130 feedback of needle insertion, and a rotaryoptical encoder 242 for needle rotation angle feedback.

A further embodiment of a needle driver is depicted in FIG. 13,employing a driver module 221′ that can hold standard needles. The drivemodule 250 further includes a fiducial frame for localization. Theneedle driver 221′ may be tracked with respect the patient, surgicalplan, and/or medical imaging system. In one configuration, imagingfiducials are incorporated into the robotic needle driver. As shown inFIG. 11, z-shaped fiducial frame 225 is incorporated into the robot baseor needle driver to localize the system with respect to the medicalimaging system. In one configuration, the system is fully compatiblewith an MRI (Magnetic Resonance Imaging) environment to enableimage-guided control of the insertion path based on intraoperative MRimages.

FIG. 14 depicts one embodiment of the system where an asymmetric tipneedle 110 is concentric with one or more additional cannulas 260-1 . .. 260-N (260 generally) or tubes, adapted to interface in a telescopingmanner or other suitable arrangement. In one configuration, at least oneof the concentric cannulas 260 is made of a shape memory material and isprecurved. In the configuration shown in FIG. 14, one rigid outercannula 262 that is positioned in the tissue, one precurved nitinol tubethat is manipulated inside the outer cannula 262 using a curved cannulaactuation unit 120′. A further solid or hollow needle or cannula 110′with an asymmetric tip is manipulated inside of the precurved cannula260 using the inner needle actuation unit. The actuation units 120′,120″ provide insertion and rotation of the corresponding needle in thisembodiment. Note that this represents an exemplary case and thatmultiple straight, precurved or prebent, and asymmetric tip needle 144,cannulas, tubes, rods, and other instruments may be cascaded together.The asymmetric needle 144 may be controlled using the approach describedin the disclosed configuration. This control may be used after initialpositioning via positioning stage 263 of the concentric delivery tubes260, or may be used to provide additional control of the needleinsertion path 152 as the concentric cannulas 260 are inserted.

FIG. 15 depicts one exemplary embodiment of a robotic needle drivercapable of manipulating both a precurved cannula 260 and an asymmetrictip needle 144. This apparatus 270 can be controlled using the approachdiscussed above. The asymmetric tip 144 may be used to control theinsertion of the inner needle after being positioned, or to manipulatethe path 152 during insertion of the precurved cannula component 260. Inone configuration, the inner needle 110 may be a hollow core needle orcannula. The asymmetric tip may be on the inner stylet, the outercannula of the needle, or both. The modular, reconfigurable needledriver is composed of 2 or more motor actuation units 120-1, 120-2 eachcapable of 2 degrees of freedom (rotation and translation of the needleor tube) capable of controlling two needle components (cannulated andinserted through the cannulated bore 110′). In one configuration, theouter cannula is precurved and the inner needle has an asymmetric tip144 that is steered as described above. Multiple tubes (cannulas 260)may be cascaded together with multiple actuation units 120-N.

FIG. 16 shows a representative teleoperation framework 300 that enablessemi-autonomous shared control of needle insertion. Semi-autonomousshared control refers to the system determining a degree of compensationto be provided, and that adjustment in the needle path 152 is madeautomatically using the disclosed approach while the user only directlycontrols the insertion depth. In an example MRI environment, a surgeon304 manipulates a user control 306, such as a teleoperation interface,haptic device, joystick, slide, knob, or any suitable control, forproviding a positioning command 305 pertaining to insertion to a roboticcontroller 302 via a master robot or other user control 306. The masterrobot or user control device 306 relays the command including positioninformation to a slave robot 310 and in turn, to the needle insertionactuator or inserter 130. Feedback force may be provided, which may takethe form of haptic feedback such as resistance of vibration, to indicatedrilling conditions to the surgeon 304, such as bone or dense tissue.Feedback force may be measured by force sensors integrated into slaverobot 310 and reflected back to the user through actuators in masterrobot 306. This may be performed under live image guidance with medicalimaging modalities including: ultrasound, x-ray, fluoroscopy, computedtomography (CT), magnetic resonance imaging (MRI), and 2D or 3D video.Guidance may also be performed using an external tracking system oradditional information from sensors on the instrument, outside the body,or in the body. One embodiment of the approach is designed to be fullycompatible with the MRI environment, wherein the user operates a masterrobot 306 from beside an MRI scanner bore, while the salve robot isinside the bore of the MRI scanner with the patient.

FIG. 17 depicts an example of a teleoperation master. Referring to FIGS.1, 16 and 17, the teleoperation master 320 may be used to control theinsertion depth of the needle by manipulating the translation stage andlinear encoder 326. As with the above configurations, insertion may becontrolled independent of the needle rotation during controlledsteering. In one embodiment, the teleoperation master 320 provides forcefeedback to the user, this may be accomplished with pneumatics or otheractuation technologies, such as via pneumatic cylinder 322. Forcefeedback may be open loop or closed loop. The master 320 may include arotary stage 324 to control either the needle rotation angle directly orthe desired steering angle of the proposed control approach. Anadditional input may be added to control steering effort. In oneembodiment, the steering angle and the steering effort are controlledautonomously while the user controls insertion depth using a hapticmaster, hence receiving feedback of needle 110 steering progress.

FIG. 18 depicts one embodiment of a needle driver module incorporating aforce sensor. Referring to FIGS. 1 and 18,a force sensor 330, disposedon an insertion module 221, may be a fiberoptic sensor such as an FPI,FBG, or light intensity-based sensor, or another sensing technologyincluding but not limited to strain gauges or load cells. Additionally,torque sensors may be used in a needle driver to estimate torsional loadon the needle. This information may be used to compensate for differencein angular position or velocity between the base and tip. In oneconfiguration, the forces measured by the force sensor are reflected tothe user through a haptic teleoperation master, as in FIG. 16.

In alternate configurations, a slave robot is actuated usingpiezoelectric motors and incorporates FPI fiberoptic force sensing. Theslave robot has a needle rotation module capable of using the proposedsteering approach. The master device measures needle translation thatcontrols slave needle insertion depth and optionally rotation that maybe used to control steering angle either directly or through theproposed steering approach. In a further configuration, force feedbackmay be provided on the haptic mater device using pneumatics or otheractuation technologies. A configuration of the system uses hybridactuation with pneumatic control of the master robot and piezoelectricactuation of the slave robot. One embodiment of the system isMRI-compatible to enable the controller, master, and slave to resideinside an MRI scanner room and be used during imaging withoutsignificantly degrading image quality.

In another arrangement, the apparatus and methods disclosed above may beintegrated into a system configuration for teleoperated control of theneedle inside the MRI scanner. In one configuration, the target istracked in interactively updated MRI images. The user control insertiondepth of the needle held by the slave robot using the master robotdevice. The user can visualize the insertion progress in interactivelyupdated MR images. In one configuration, the needle may be autonomouslysteered to reach the target, while the user only directly controlsinsertion depth or insertion speed. In this configuration, the targetand needle are tracked in interactively updated medical images, and thecontrol system uses the teachings of the resent invention to steer theneedle to the target (i.e. active compensation of the path) while theuser (e.g. a clinician) controls the insertion depth or insertion speedusing a master device while visualizing the needle insertion. Thisenables the clinician control over depth, thus potentially improvingsafety over a fully autonomous system, while enable the control systemto ensure the needle reaches the target even in the presence ofdeformation. In an alternate configuration, the needle driver robot isnot actuated along needle insertion (only position sensing along theinsertion direction), and the user directly inserts the needle bypushing on the needle driver (without a separate teleoperation master)while the rotation module autonomously steers the needle according tothe teachings of the disclosed configuration.

The above description provides detail about exemplary configurations andalgorithms of the disclosed configuration's teachings; however, thedisclosed configuration is not restricted to only the specificconfiguration or approaches shown.

The present configurations may be practiced by employing conventionalmaterials, methodology and equipment. Accordingly, the details of suchmaterials, equipment and methodology are not set forth herein in detail.In the previous descriptions, numerous specific details are set forth,such as specific materials, structures, processes, etc., in order toprovide a thorough understanding of the disclosed configuration.However, it should be recognized that the disclosed configuration can bepracticed without resorting to the details specifically set forth. Onlyan exemplary embodiment of the disclosed configuration and but a fewexamples of its versatility are shown and described in the presentdisclosure. It is to be understood that the disclosed configuration iscapable of use in various other combinations and environments and iscapable of changes or modifications within the scope of the inventiveconcept as expressed herein.

Those skilled in the art should readily appreciate that the programs andmethods defined herein are deliverable to a user processing andrendering device in many forms, including but not limited to a)information permanently stored on non-writeable storage media such asROM devices, b) information alterably stored on writeable non-transitorystorage media such as floppy disks, magnetic tapes, CDs, RAM devices,and other magnetic and optical media, or c) information conveyed to acomputer through communication media, as in an electronic network suchas the Internet or telephone modem lines. The operations and methods maybe implemented in a software executable object or as a set of encodedinstructions for execution by a processor responsive to theinstructions. Alternatively, the operations and methods disclosed hereinmay be embodied in whole or in part using hardware components, such asApplication Specific Integrated Circuits (ASICs), Field ProgrammableGate Arrays (FPGAs), microcontrollers, state machines, controllers orother hardware components or devices, or a combination of hardware,software, and firmware components.

While the system and methods defined herein have been particularly shownand described with references to embodiments thereof, it will beunderstood by those skilled in the art that various changes in form anddetails may be made therein without departing from the scope of theinvention encompassed by the appended claims

1. In a surgical environment having an asymmetric tipped needle and aneedle driving apparatus responsive to rotational control, a method ofdirecting the needle comprising: identifying a steering path for theneedle; controlling a time-varying rotation speed of the needle based onthe identified steering path, the rotation speed determining a relativeduration that a bevel angle of the needle applies force in a directioncorresponding to the steering trajectory; and decoupling advancement ofthe needle from control of the rotation speed about the needle axis,such that the controlled rotation speed is based on an angle of rotationindependent of advancement of the needle.
 2. The method of claim 1further comprising defining an asymmetric tip from a bevel cut across atleast a portion of a cylindrical needle, the bevel cut forming an angleand a bevel face on the needle tip.
 3. The method of claim 1 whereindecoupling further comprises decoupling the rotation speed from thelinear advancement by underactuated control of the needle such thatcurvature and direction of an insertion path is controlled based ondetermining the angular velocity as a function of the rotation angle asthe needle rotates continuously.
 4. The method of claim 1 furthercomprising: inserting the asymmetric tip into a tissue medium, themedium exerting a normal force on the asymmetric tip resulting from abeveled angle on the asymmetric tip; and controlling the rotation speedbased on a rotational position of the asymmetric tip such that therotation speed disposes the bevel face against the medium for directingthe needle in the direction corresponding to the steering path.
 5. Themethod of claim 4 wherein the controlled rotation speed disposes thebevel face for a longer time in a direction corresponding to the desiredsteering direction, the bevel angle providing a steering force againstthe medium.
 6. The method of claim 1 wherein controlling the rotationspeed includes varying the rotation speed such that the rotation speeddefines a relative duration that a bevel face of the asymmetric tipapplies steering force in a particular direction, wherein an extent ofcurvature and the direction angle of the needle are controlled via asingle actuator.
 7. The method of claim 1 further comprising: defining acomplex path for the needle by aggregating a plurality of curvedsteering paths, each steering path defined by an arc, direction, anddistance.
 8. The method of claim 7, further employing a closed loopmonitoring to maintain rotational control for each of the plurality ofsteering paths along the complex path or to reach the predeterminedtarget location.
 9. The method of claim 1 further comprising:controlling needle advancement based on a signal received from amanually actuated user interface unit; and controlling needle rotationbased on angular position and the steering path, the needle rotationindependent of the manual actuation signal.
 10. The method of claim 4further comprising: identifying angular rotation by receiving signalsfrom an optical encoder attached to the needle; and adjusting therotation speed based on the received signals.
 11. The method of claim 4further comprising: identifying insertion depth by receiving signalsfrom an optical encoder attached to the needle; and updating the desiredpath based on the insertion depth.
 12. The method of claim 3 furthercomprising: sensing forces exerted on the needle by the tissue medium;and providing haptic feedback based on the sensed forces to an operator.13. The method of claim 1 further comprising disposing the needle usinga 2 degree-of-freedom (DOF) drive for controlling rotation and insertionfor providing a 3 DOF targeting ability for steering the needle to atarget.
 14. The method of claim 1, wherein the needle driving apparatusis underactuaed and capable of controlling needle direction angle,curvature, and insertion depth from two actuators.
 15. The method ofclaim 14, wherein control of needle direction angle and needle curvatureis decoupled from control of needle insertion depth, wherein it is notrequired to coordinate needle insertion motion with needle rotationmotion.
 16. A needle steering apparatus comprising: a needle having anasymmetric tip, the asymmetric tip defined by a beveled cut across acylindrical cross section of the needle; a rotary drive for rotating theneedle along a needle axis, the rotary drive responsive to control logicadapted to rotate the needle at an angular velocity based on an angularposition; and an inserter for disposing the needle axially in adirection of an axis of rotation, the angular velocity independent fromthe insertion.
 17. The apparatus of claim 16, wherein the control logicenables independent control of the rotary driver from that of theinserter.
 18. The apparatus of claim 16, wherein the control logicenables underactuated control of both curvature and direction of aneedle path from a single rotary drive.
 19. The apparatus of claim 16further comprising a teleoperation master device configured forproviding control of the inserter motion.
 20. The teleoperation controlof claim 19, wherein the teleoperation master is responsive to physicalcounterforce on the needle for providing corresponding feedback to auser.
 21. The apparatus of claim 16 further comprising one or moreadditional drives and a cannulated delivery mechanism, the cannulateddelivery mechanism configured to define a cannula for at least a portionof a path to a surgical target, the cannula responsive to insertion ofthe needle for disposing the needle beyond an end of the cannula. 22.The apparatus of claim 16 further comprising a needle driver, the needledriver for controlling rotation and insertion, the needle drivermechanically coupled to a fiducial frame for locating the needle driverrelative to a patient, medical images of a patient, and/or a surgicalplan.
 23. A method for inserting a needle with an asymmetric shaped tipinto tissue along a curved path, wherein the needle is continuouslyrotated at a time-varying angular velocity; wherein the time-varyingangular velocity rotation is a function of the needle angular position.24. The method of claim 23, wherein the time-varying angular velocity ofthe needle is controlled such that one actuator provides for control ofboth needle curvature and needle direction angle.
 25. The method ofclaim 24, wherein control of the rotation of the needle is decoupledfrom control of the needle insertion motion along the length of theneedle.
 26. The method of claim 24, wherein needle curvature and needleinsertion direction are controlled independently from needle insertion.27. The method of claim 26, wherein needle insertion is manuallycontrolled by a user.
 28. The method of claim 27, wherein needle depthis controlled through a teleoperation interface and needle curvature anddirection are controlled automatically.
 29. The method of claim 28,further comprising incorporation of haptic feedback to the user throughthe teleoperation interface to reflect needle insertion forces or otherfeedback relating to the needle insertion process.
 30. The method ofclaim 23 wherein a user controls needle insertion depth, wherein anautomatic control system controls needle direction and curvature tomaintain a path to a target location.
 31. The method of claim 23,wherein an automatic control system directs two actuators based onclosed loop imaging feedback; further comprising a first actuator forcontrol of needle insertion depth; and a second actuator for needledirection and curvature; wherein the automatic control system directsthe needle to maintain a path to a target location.
 32. The method ofclaim 23 further comprising manual control of the needle insertionthrough the use of a handheld instrument.
 33. The method of claim 32,wherein the handheld instrument controls continuous needle rotation anda user manually controls needle insertion.
 34. The method of claim 31,wherein the automatic control system manages the needle trajectory basedon imaging feedback to provide closed loop control of the needletrajectory to reach a target.
 35. The method of claim 24, wherein theneedle with asymmetric shaped tip is inserted through one or moreprecurved concentric tubes, wherein the precurved concentric tubesprovide initial guidance of the needle trajectory and the needle withasymmetric shaped tip is controlled for precision placement of theneedle tip as the needle approaches a target location.
 36. The method ofclaim 23 further comprising: inserting a needle via a control having atleast two degrees of freedom, each of the degrees of freedom independentfrom the other degrees of freedom; and one of the degrees of freedombeing responsive to an angular position for rotating the needle at atime varying angular velocity.